LONDON, U.K. - As the battle to woo banking and financial services giants post-Brexit, between top cities in the European Union intensifies, now, a leaked memo has revealed a shocking accusation.

France, that has been trying to lure top financial, banking and investment giants looking to set up a post Brexit EU hub has been accused of plotting to sabotage the British economy.

Reports revealed that the memo was written after the City of London’s Brexit envoy – former Home Office Minister Jeremy Browne, earlier this month held talks in Paris at the French finance ministry, state-owned Banque de France, the French Senate and the British Embassy.

Browne, who met banking chiefs, senior politicians and diplomats, conveyed a message to the U.K. Treasury Ministers and MPs that claims Macron’s France has effectively declared open war on London’s Square Mile.

He warned, “They are crystal clear about their underlying objective: the weakening of Britain, the on-going degradation of the City of London.”

The leaked memo that was sent to Ministers claims that the French government and banking chiefs are plotting to “actively disrupt and destroy” the U.K.’s multi-billion-pound financial sector when Britain leaves the EU - even if France gains nothing.

According to the memo, France has boasted to City of London chiefs that it will use Brexit to sabotage the British economy.

The missive reportedly blames the ‘giddy’ effect of newly elected President Emmanuel Macron, for an “assertive collective endeavour” to wreck the City, which is worth 66 billion pounds a year to the Treasury in tax receipts.

Browne, who was a Lib Dem Minister in David Cameron and Nick Clegg’s Coalition, serving in the Foreign Office and Home Office, reportedly pointed to “French representatives crashing around London” offering big sums to firms to move to Paris.

Earlier this month, Macron appointed Bruno Le Maire as the French finance minister and lauded him for saying Brexit provided a “fabulous opportunity for France.”

Browne said that the country’s banking bosses are just as belligerent.

He wrote in the memo, “The meeting with the French Central Bank was the worst I have had anywhere in the EU. They are in favour of the hardest Brexit. They want disruption. They actively seek disaggregation of financial services provision.”

Browne further noted, “The clear messages emanating from Paris are not just the musings of a rogue senior official in the French government or central bank. France could not be clearer about their intentions. They see Britain and the City of London as adversaries, not partners.”

According to reports, the memo also suggested that other EU nations, who wanted good relations with the U.K. over Brexit were alarmed by France’s hostile conduct but were powerless – or unwilling – to stop them.

Browne pointed out, “There is plenty of anxiety elsewhere in the EU about the French throwing their weight around so aggressively, but their destructive impulses are not being confined, and other EU countries that want a friendly relationship with Britain and the City of London are being marginalised.”

He claimed, the French were “commendably honest about their true intentions – which makes the exchanges more meaningful.”

Browne even hinted they were acting out of spite, “making a virtue of rejecting a partnership with Britain and happy to see outcomes detrimental to the City – even if Paris is not the beneficiary.”

He warned, make no mistake, France sees the U.K. and the City “as adversaries, not partners.”

Browne explained, it was much more serious than the wily French merely putting down a Brexit talks marker as “the opening shots in a long negotiating process.”

He said, French industry was barely more conciliatory than French finance and banking, and offered no “life raft” for Britain. “They were,” he said, “by a big margin, much worse than the norm elsewhere in the EU.”

Browne then urged that the Government must do more to combat the French threat by “putting some more balls back on the other side of the court.”

He also said the Government should be "honest" about the scale of the challenge and the need for an extended period of transitional arrangements after the U.K. leaves in 2019 while a final settlement is agreed.

Adding, “There is no chance all the details will be hammered out in 20 months. We will need a long transition phase and the time needed does not diminish by pretending that this phase is just about 'implementing' agreed policies as they will not all be agreed."